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Nov132016

13 November, 2016 - NNE of Amberley, New Zealand (M7.8)

A large, M7.8, earthquake occurred beneath the South Island of New Zealand. The aftershocks stretch across a zone along NE edge of the island for about 175-200 km.

 

You can watch the aftershocks on three stations near the rupture zone, SNZO in Wellington (to the north), KHZ near the middle of the aftershock zone), and RPZ (to the south). Here is the channel list

SIGNALPARAMETERS; 2016-11-13 15:23:58; -30;  10; 0.5; -4.0 
IU; SNZO; 00; BHZ; WELLINGTON, NEW ZEALAND (UP-DOWN)
IU; SNZO; 00; BH2; WELLINGTON, NEW ZEALAND (EAST-WEST)
IU; SNZO; 00; BH1; WELLINGTON, NEW ZEALAND (NORTH-SOUTH)
NZ; KHZ; 10; HHZ; KAHUTARA, NEW ZEALAND (UP-DOWN)
NZ; KHZ; 10; HHE; KAHUTARA, NEW ZEALAND (EAST-WEST)
NZ; KHZ; 10; HHN; KAHUTARA, NEW ZEALAND (NORTH-SOUTH)
NZ; RPZ; 20; BNZ; RATA PEAKS, NEW ZEALAND (UP-DOWN)
NZ; RPZ; 20; BNE; RATA PEAKS, NEW ZEALAND (EAST-WEST)
NZ; RPZ; 20; BNN; RATA PEAKS, NEW ZEALAND (NORTH-SOUTH)

Below is a view of the recent aftershocks on the three stations.


To look at the mainshock, you want to use the strong motion channels

IU; SNZO; 20; hnz; WELLINGTON, NEW ZEALAND (UP-DOWN)
IU; SNZO; 20; hn2; WELLINGTON, NEW ZEALAND (EAST-WEST)
IU; SNZO; 20; hn1; WELLINGTON, NEW ZEALAND (NORTH-SOUTH)
NZ; KHZ; 20; BNZ; KAHUTARA, NEW ZEALAND (UP-DOWN)
NZ; KHZ; 20; BNE; KAHUTARA, NEW ZEALAND (EAST-WEST)
NZ; KHZ; 20; BNN; KAHUTARA, NEW ZEALAND (NORTH-SOUTH)
NZ; RPZ; 20; BNZ; RATA PEAKS, NEW ZEALAND (UP-DOWN)
NZ; RPZ; 20; BNE; RATA PEAKS, NEW ZEALAND (EAST-WEST)
NZ; RPZ; 20; BNN; RATA PEAKS, NEW ZEALAND (NORTH-SOUTH)

The mainshock recordings to the north and to the south are shown below. The plots show the graound velocity and the numbers on the right are in miconrs/second, but the instrument response has not been removed. Only a gain correction applied. The ground velocities (particularly the S/Surface waves) are much larger towards the north than the south, consistent with a northward directed rupture, as indicated by the hypocenter, aftershocks, and early USGS finite fault model. But Rata Peaks is quite a bit farther south than Wellington is to the north. So distance plays some role in the comparison as well.